When it comes to strengthening your core you don't need to work your abdominal muscles to complete exhaustion. Yep, you don't have to be so hardcore when it comes to getting a hard core. By focusing on effective exercises (read: not performing mindless crunches or holding a plank for so long that good form is a concept versus a reality), you can see the abs results you're after.

Of course, it takes both smart training and a healthy diet to develop a rock-solid core. But consider these nine bodyweight exercises lesson one. Core school is now in session.